Re: She doesn't want it, but I do...
Then I'd consider her a "dead end" as far as sex goes. You might tell if that since sex isn't going to be in the cards with her, you'll consider that tacit approval for you to find somebody else to have sex with if you'd like. This shouldn't be used as a "bargaining chip", mind you. It's just that if she wants to be asexual, that's totally her call, but that shouldn't force you into that role as well.